It says that it is 170 GB of apps is taking up space on my C drive but i can not find near everything that is taking up space. What do i do?

First off about 15% of the files on a computer are "hidden" for security reasons. You can unhide them of course but that opens a vulnerability. Also Minecraft  automatically saves the server's chat history on the server you are on and saves screenshots. %appdata%>.minecraft That won't take anywhere nearly 170GB maybe 2 GB. Fortnight takes like 7GB. Anyways, it also may be showing you those "hidden files" I mentioned and everything else on your computer such as C:\Program Files and C:\Program Files (x86) and files left behind when you uninstall a program. I would be able to give you a more definitive answer but i would need to see exactly what it says and what it showed you.

The first thing I would do is to run "Disk Cleanup". Located at 

C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Administrative Tools

in Win 10. It will clean up all of your temp files and gives you the option to clean up "System Files".  This will remove all of the past Win 10 install files.

I suspect that will get you cleaned up.

Whatever is telling you this is trying to get you to buy it's software to "fix" the issue. That is corporate fishing from Microsoft and/or Google. If you know what you have installed on your PC, then don't you worry. What you should do instead is uninstall the antivirus or security software that's in your system. Or, change the settings to stop checking for "Excess or Unused Software". That's another reason why Windows is crap.

Delete apps you no longer need, and if you have an HDD do a disk defrag

Download Treesize?

Don't know what OS you are using, C:\ is the root that has the OS as well as program files. Some apps that save files and cashes default the install drive and that can build a lot over time.

I use MS Win 10, MS has file explorer where you can select folders in a tree an get properties like number and size of files or folders. Hidden folders have to be set to unhide, but you see everything but system folders. That can clue you what is hoarding your disc. 200GB is not a big drive for storing data, if this is a partition drive and have a D: drive, that is where your data files belong. You can change 'where' data is to be stored in your individual app setting, and external or thumb drives are common.

Under disc manager, it should show total drive space and partitioned logical drives if any. If the total is 200 Gb on one partition, you might think an external HDD for the data files/folders. About the only other option is a larger HDD.

Some years back, I started loosing a huge chunk of space, turns out a silent trojan was using MY computer to store and spread spam and torrent. Took a bit of work to locate the trojan and rid it then just deleted the huge folder and got my space back.

Some older OSs also used disc space for page file, a needed evil with little memory.

popups saying running low on memory are clue to this.

Hope this point you in the right direction.

if you have 170GB of data, it is almost certainly video. click on any video apps, and Reset them to clear their caches.

i bet YouTube takes up a truckload...

"Apps" means applications. Things such as software and plug-ins. MS Edge for example is a 184 MB application. If you need space you need to clear out un-used programs. I don't know of any single app that could be that large. But I do see how I could free up space on my unit just by deleting a few programs I never use that were factory installed.

Here is the rub- I have had to fix a lot of computers because some one deleted the wrong app. It would be better in the long run if you need space to just add another hard drive.

you could take it to a computer place and let them fix it

Download a disk space mapping utility, which will show you which folders are taking up the most space on your disk. An example of one such utility is TreeSize Free, you can google it yourself.

Typically in a Windows PC, the Windows OS itself takes a large portion of the disk, around 30-50 GB. Then the other big folders are the "Users" folder, where all of your personal data resides. The other one would be "Program Files", where all of the apps reside. TreeSize will show you in ranked order which is taking up the most of your storage space.